In a coating product spraying installation, it is known to spray the product by means of a rotary element, called a bowl or dish, supplied with product and rotating at a speed usually included between 2,000 and 120,000 rpm. At the speeds in question, the bowl must be as light and balanced as possible in order to avoid unbalance to a maximum, particularly if its means for driving in rotation comprise an air and/or magnetic bearing turbine.
It is known, for example from WO-A-94/12286, to connect a bowl to a rotor by means of a fitting ring capable of radial expansion. It is also known, for example from WO-A-01/62396, to use magnetic coupling means between a bowl and the rotor of a turbine. These coupling means comprise permanent magnets which are relatively complex to assemble on the bowl or on the rotor of the turbine, particularly in order to avoid these magnets bursting under the effect of the centrifugal force. Such assembly most often prevents a rapid replacement of the magnetic coupling magnets. In addition, the balance of the rotating parts must be as perfect as possible in order to limit the effect of the forces of inertia. The or each magnet used must therefore be balanced in rotation, which is delicate to effect, as the material constituting the magnet or magnets does not have an isotropic density and because such a material is brittle, therefore difficult to machine.
It is a particular object of the invention to overcome these drawbacks by proposing a spraying bowl which may be easily driven by a rotor provided to that end thanks to an efficient magnetic coupling, without requiring the assembly of permanent magnets on a rotating part of the sprayer.